Brittleness didn't get talked about enough. I couldn't figure out why my fundament was breaking on retraction to my Creality Hi CFS over and over again. It was driving me nuts. The prints all came out looking great, so I thought I wasn't having humidity issues and that there was a mechanical problem somewhere. Took the whole damn thing apart to clean and check that everything was tightened to correctly. Multiple times.

I just needed a filament dryer.

I had no idea that filament snapping on retraction could be caused by wet filament, and I read about 3D printing a lot more than most. Almost all threads about wet filament are about print quality, and people rarely mention brittleness. Conversely, in threads about filament jams/errors, most comments focus on the mechanical parts (tension, loose screws, debris in the gears, temps, etc.) and rarely mention wet, brittle filament as a possible cause.

If you're reading this and don't have one (or another method for it), get a filament dryer. I recommend the Creality one when it goes on sale as it's one of the cheapest options that can hit the high temps needed for some filaments and that can also be used as a dry box you can print from. My only gripe is needing to prop the lid open when it's drying to release the humidity. It's silly that it can't dry filament properly without the door cracked open.